Donor-acceptor oligothiophenes as low optical gap chromophores for photovoltaic applications

The synthesis and characterization of novel hole-transporting and narrow HOMO-LUMO energy gap oligothiophenes that are asymmetrically endcapped with diphenylaminofluorenyl and dicyanovinyl groups,and their potential for photovoltaic applications was reported. Malonitrile was added to a 100 mL two-necked flask containing 5a and 10 mL chloroform at room temperature. After stirring for three minutes, pyridine was added to the mixture which resulted in an immediate change in color. The combined organic extracts were dried over Na₂SO₄ and after removal of Na₂SO₄ by filtration, chloroform soluble filtrates were concentrated and precipitated with diethyl ether. The findings suggests that extended donor-acceptor oligothiophenes, which exhibit a narrow optical energy gap are promising p-type semiconducting photosensitizers for high performance photovoltaic applications.